Cold deposition coating device and method for formamidino halide material

Abstract

The invention relates to the technical field of perovskite solar cell film preparation, in particular to a formamidino halide material cold deposition coating device and method.The formamidino halide material cold deposition coating device comprises a shell, an evaporation source and a substrate support, the evaporation source and a substrate are both located in the shell, a heating belt is embedded in the shell, the evaporation source is arranged in the center of the shell, and the substrate support is arranged on the substrate support; the heating belt and the evaporation source are subjected to temperature control in an independent electric heating mode; the substrate support is arranged around the evaporation source according to the design position of the cavity; a cooling structure is arranged in the substrate support, substrate clamps are arranged on the two faces of the substrate support, a substrate is fixed to the substrate clamps, and a rotating structure is arranged at the bottom of the substrate support. The interior of the shell further communicates with a vacuum pump. During use, the temperature of the shell is higher than that of the substrate support. According to the method, the formamidino halide material in a dispersed state is most easily deposited in a low-temperature region, and the preferential deposition and accurate control of the formamidino halide material can be realized by designing a variable-temperature and rotatable substrate device.

Description

Technical Field

[0001] The invention relates to the technical field of perovskite solar cell thin film preparation, and in particular to a formamidinium-based halide cold deposition coating device and method. Background Art

[0002] Perovskite solar cell thin film is a solar cell that uses perovskite material as a light-absorbing layer. Its structure usually includes five parts: a transparent conductive electrode, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode. Perovskite material, as a light-absorbing layer thin film, can efficiently complete the processes of absorbing sunlight, exciting, transporting, and separating photogenerated carriers. Perovskite solar cell thin film is generally prepared by a deposition method using a spin coater, an evaporation coating device, a spray coating device, or a slit coating machine.

[0003] In perovskite solar cells, the vast majority of perovskite film preparations are wet-processed, such as spin coating, slit coating, spray coating, etc. It is difficult to completely remove the solvent in the wet-process perovskite film preparation, because there are still many problems with the film stability. The evaporation preparation of perovskite film has great advantages in stability because there is no solvent involved. However, the evaporation preparation of perovskite film is difficult to ensure its reliable repeatability in the preparation of guanidine halide materials. The main reason is that the guanidine halide material is different from other materials in that after heating and gasification, it is not deposited on the substrate in a linear state, but floats in the entire cavity in a diffuse state, so it is difficult to accurately control the deposition process of this type of material. In view of these problems, the present invention adopts a series of specific schemes, which can quickly and effectively deposit guanidine halide materials, not only speed up the beat of film preparation, but also obtain a perovskite film with excellent stability. Summary of the invention

[0004] In view of the problem in the prior art that formamidinium halide materials are difficult to deposit because they are in a dispersed state when heated, the present invention provides a cold deposition coating device and method for formamidinium halide materials.

[0005] The present invention is achieved through the following technical solutions: A cold deposition coating device for formamidinium halide material comprises a shell, an evaporation source and a substrate holder, wherein the evaporation source and the substrate are both located inside the shell, the formamidinium halide material is placed in the evaporation source, a heating belt is embedded inside the shell, the evaporation source is arranged at the center of the shell, and the heating belt and the evaporation source are temperature-controlled by separate electric heating methods; the substrate holder is arranged around the evaporation source according to the design position of the cavity; a cooling structure is arranged inside the substrate holder, substrate clamps are arranged on both sides of the substrate holder, the substrate is fixed on the substrate clamps, and a rotating structure is arranged at the bottom of the substrate holder; a vacuum pump is also connected inside the shell; when in use, the temperature of the shell is higher than that of the substrate holder.

[0006] Preferably, the rotating structure includes a rotating motor, a rotating base and a support rod. The shell of the rotating motor is fixed to the outer bottom of the shell. The output end of the rotating motor passes through the bottom of the shell and is fixedly connected to the bottom of the rotating base. One end of the support rod is fixedly connected to the rotating base, and the other end is connected to the bottom of the substrate holder.

[0007] Preferably, the support rod has a hollow structure, and the cooling structure includes a liquid inlet pipeline, a regulating pipeline and a liquid outlet pipeline, the liquid inlet pipeline and the liquid outlet pipeline are both located in the support rod, one end of the liquid inlet pipeline is connected to the external liquid tank, and the other end is connected to the liquid inlet end of the regulating pipeline, the regulating pipeline is embedded in the substrate support, the liquid outlet end of the regulating pipeline is connected to the liquid inlet end of the liquid outlet pipeline, and the liquid outlet end of the liquid outlet pipeline is connected to the external liquid tank; the external liquid tank contains cooling liquid, and a temperature control electrode is provided at the bottom of the external liquid tank, and the temperature control electrode is connected to an external power supply.

[0008] Preferably, the regulating pipeline is arranged in a serpentine shape inside the substrate holder.

[0009] Preferably, a partition is provided inside the support rod, and the liquid inlet pipeline and the liquid outlet pipeline are respectively located on both sides of the partition.

[0010] Preferably, a flow regulating valve is provided on the liquid inlet pipeline.

[0011] Preferably, a crystal oscillator is arranged on the substrate holder.

[0012] Preferably, the substrate clamp comprises a first fixing bar and a second fixing bar, the first fixing bar and the second fixing bar are connected to a vertical surface of the substrate holder in parallel and at intervals, and the substrate is clamped between the first fixing bar and the second fixing bar.

[0013] Preferably, the first fixing bar and the second fixing bar are slidably arranged on the substrate holder via an elastic element, and the telescopic axis of the elastic element is perpendicular to the length axis of the first fixing bar.

[0014] A cold deposition preparation method for formamidinium halide materials, using the cold deposition coating device for formamidinium halide materials, the preparation method utilizes the fact that formamidinium halide materials in a dispersed state are most likely to be deposited first in a region with a lower temperature, and a variable temperature and rotatable substrate device is designed to achieve preferential deposition and precise control of the formamidinium halide materials, and specifically comprises the following steps: S1, fixing the deposition surface of the substrate in a substrate fixture of the substrate holder in a back-to-back manner; S2, turning on the heating switches of the evaporation source and the heating belt at the same time, so that the formamidinium halide material is vaporized, and the temperature of the shell and the cavity is increased, and the temperature inside the cavity is controlled within 100-250°C; S3, rotating the substrate holder, opening the cooling structure to cool the substrate, when the temperature of the substrate is lower than the internal temperature of the cavity, the formamidinium halide material begins to deposit on the surface of the substrate, completing the preparation of the formamidinium halide film.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The cold deposition coating device of carboxamidine halide material of the present invention realizes uniform deposition of thin film by setting a plurality of rotatable substrate holders. The double-sided substrate holder can effectively utilize the cavity space. The cooling structure embedded in the middle of the substrate holder can quickly cool down the substrate to obtain the best temperature gradient difference, which is beneficial to the characteristics of hot amino halide and cold rapid deposition, and can quickly obtain high-quality thin film. The distribution and quantity of substrate positions are key, which restricts the quality of perovskite thin film and the rhythm of component preparation. The substrate holder adopts an octagonal symmetrical distribution, and substrates can be placed on both sides for preparation, so as to realize the high-throughput preparation of perovskite thin film layer in vacuum perovskite solar cell.

[0016] Furthermore, the rotating structure is used to drive the substrate holder to rotate. When the rotating motor is turned on, the rotating motor drives the rotating base to rotate, the rotating base drives the support rod to rotate, and the support rod drives the substrate holder to rotate, thereby achieving uniform deposition of the thin film.

[0017] Furthermore, the support rod of the hollow structure provides an installation position for the liquid inlet pipeline and the liquid outlet pipeline. The coolant enters the regulating pipeline from the external liquid tank through the liquid inlet pipeline. The coolant entering the regulating pipeline can cool the substrate holder, and then cool the substrate. The coolant then returns to the external liquid tank through the liquid outlet pipeline, so that the coolant can be recycled. The external liquid tank, the liquid inlet pipeline, the regulating pipeline and the liquid outlet pipeline form a closed circulation temperature control system. Combined with the temperature control electrode of the external liquid tank, the temperature of the coolant can be controlled, thereby realizing the temperature control of the substrate.

[0018] Furthermore, the serpentine arrangement of the regulating pipeline can increase the contact area between the regulating pipeline and the substrate holder, which helps to achieve uniform temperature distribution on the substrate holder, enhances the heat exchange efficiency between the liquid and the substrate holder, and makes the temperature regulation of the substrate more rapid and accurate.

[0019] Furthermore, the partition can not only increase the strength of the support rod, but also separate the liquid inlet pipeline and the liquid outlet pipeline to prevent heat exchange and shape change between the two, which would affect temperature control, thereby maintaining a clear path and flow direction of the fluid.

[0020] Furthermore, the flow regulating valve can be provided to accurately control the flow of the cooling liquid in the entire pipeline, thereby achieving accurate temperature regulation, thereby more effectively controlling the temperature of the substrate holder and the substrate, and reducing temperature fluctuations and deviations.

[0021] Furthermore, the crystal oscillator can detect the thickness of the thin film on the substrate, which facilitates the precise control of the thin film.

[0022] Furthermore, the first fixing bar and the second fixing bar are used to fix the substrate to ensure stable support of the substrate. The first fixing bar and the second fixing bar connected by sliding of the elastic element can fix substrates of different sizes, which has more flexible versatility and practicality.

[0023] The present invention utilizes that the formamidinium halide material is in a diffuse and irregular state after being vaporized under heating or high-energy ion collision conditions, in which the film deposition rate is slow, the control is difficult, and the thickness is inaccurate. One of the key points of the present invention is that, according to multiple experiments, the formamidinium halide material in a diffuse state is most likely to be deposited first in a region with a lower temperature, and the design of a temperature-variable and rotatable substrate device can achieve preferential deposition and precise control of the formamidinium halide material. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of a cold deposition coating device of a formamidinium-based halide material according to the present invention; Figure 2 It is a schematic diagram of another viewing angle of a cold deposition coating device of a formamidinium-based halide material of the present invention; Figure 3 It is a schematic diagram of a substrate holder in a cold deposition coating device of a formamidinium-based halide material according to the present invention; Figure 4 The present invention is a schematic diagram of assembling a substrate holder and a substrate in a cold deposition coating device for formamidinium-based halide materials.

[0025] In the figure, 1. shell; 2. evaporation source; 3. substrate holder; 4. rotating base; 5. support rod; 6. adjustment pipeline; 7. first fixing bar; 8. second fixing bar; 9. slot; 10. liquid inlet pipeline; 11. liquid outlet pipeline. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0027] The present invention discloses a cold deposition coating device for a formamidite halide material, referring to Figure 1, including a shell 1, an evaporation source 2 and a substrate holder 3, the evaporation source 2 and the substrate are both located inside the shell 1, the guanidine halide material is placed in the evaporation source 2, a heating belt is embedded inside the shell 1, the evaporation source 2 is arranged at the center of the shell 1, and the heating belt and the evaporation source 2 are temperature controlled by a separate electric heating method. The shell 1 is used to provide a closed deposition environment for the separate deposition of the guanidine halide material, so it is named a sub-cavity. The shell 1 can be arranged linearly or in clusters with inorganic materials, such as lead halide materials and cesium halide materials. In this embodiment, three evaporation sources 2 are provided, and are evenly arranged on the same circumference with the center of the internal cavity of the shell 1 as the axis, and the evaporation source 2 and the heating belt are independently temperature controlled to achieve accurate evaporation and deposition processes. At the same time, the shell 1 is provided with a temperature hole probe installation hole, so as to install a temperature sensor to monitor the cavity temperature in real time and achieve accurate temperature regulation.

[0028] The substrate holder 3 is arranged around the evaporation source 2 according to the design position of the cavity; in this embodiment, the shell 1 adopts an octagonal shell 1; there are eight substrate holders 3, and they are arranged symmetrically according to the octagonal corresponding position of the shell 1. The octagonal design of the shell 1 not only provides structural stability, but also optimizes the utilization of the internal space, so that the evaporation source 2 can radiate heat to the surrounding more effectively, thereby improving the evaporation efficiency. In this embodiment, the substrate holder 3 is arranged vertically, but is not limited to the vertical setting. It can also be placed horizontally or at other angles, which is conducive to the uniform distribution of the deposition material on the substrate, improves the deposition quality, and facilitates the installation, removal and replacement of the substrate. The eight substrate holders 3 are arranged symmetrically according to the corresponding positions of the octagonal shell 1, ensuring that each substrate can receive uniform heat from the evaporation source 2, which helps to improve the uniformity and consistency of the deposition process. At the same time, the simultaneous use of multiple substrate holders 3 enables the system to process multiple substrates at the same time, thereby improving production efficiency.

[0029] The substrate holder 3 is provided with a cooling structure inside, which includes a liquid inlet pipeline 10, a regulating pipeline 6 and a liquid outlet pipeline 11. One end of the liquid inlet pipeline 10 is connected to the external liquid tank, and the other end is connected to the liquid inlet end of the regulating pipeline 6. The regulating pipeline 6 is embedded in the substrate holder 3. The liquid outlet end of the regulating pipeline 6 is connected to the liquid inlet end of the liquid outlet pipeline 11, and the liquid outlet end of the liquid outlet pipeline 11 is connected to the external liquid tank. The external liquid tank contains cooling liquid, and a temperature control electrode is provided at the bottom of the external liquid tank, which is connected to an external power supply. The cooling liquid can be other heatable cooling media such as water, alcohol, thermal oil, etc. The regulating pipeline 6 is arranged in a serpentine shape inside the substrate holder 3, and a flow control valve is provided on the liquid inlet pipeline 10. The liquid inlet pipeline 10, the regulating pipeline 6, the liquid outlet pipeline 11 and the external liquid tank together form a temperature control circulation system. The liquid inlet pipeline 10 introduces the cooling liquid from the external liquid tank, and sends the cooling liquid to the area requiring temperature control-the substrate through the regulating pipeline 6. The cooling liquid flows along the regulating pipeline 6 arranged in a serpentine shape, and the temperature is regulated by heat exchange with the substrate holder 3. After that, the cooling liquid returns to the external liquid tank through the liquid outlet pipeline 11, and the temperature is adjusted through the temperature control electrode, and then enters the next cycle through the liquid inlet pipeline 10 again. The temperature control electrode adjusts the temperature of the cooling liquid by controlling the on and off of the power supply and the current, thereby realizing the control of the temperature of the cooling liquid, and then realizing the precise control of the substrate holder 3 and the substrate temperature. At the same time, the regulating pipeline 6 arranged in a serpentine shape greatly increases the contact area with the substrate holder 3, and is more evenly distributed inside the substrate holder 3, thereby ensuring that each part on the substrate holder 3 can be affected by the temperature control liquid, and can adapt to substrate holders 3 of different shapes and sizes, with the characteristics of high efficiency, compactness and flexibility.

[0030] The substrate holder 3 is provided with a substrate clamp on both sides, and the substrate is fixed on the substrate clamp. The substrate clamp includes a first fixing bar 7 and a second fixing bar 8, which are parallel to and spaced from the vertical surface of the substrate holder 3, and the substrate is clamped between the first fixing bar 7 and the second fixing bar 8. In this embodiment, a clamping slot 9 is provided on the opposite side of the first fixing bar 7 and the second fixing bar 8, and the end of the substrate is clamped with the clamping slot 9. Since the substrate is arranged on the substrate holder 3 by rotating 90°, a stopper is provided at the lower end of the clamping slot 9 of the first fixing bar 7 and the second fixing bar 8 to prevent the substrate from falling off from the clamping slot 9. The position of the substrate on the substrate holder 3 is not limited to the position shown in the drawings of the present invention, and it is sufficient to ensure that the substrate does not fall off from the first fixing bar 7 and the second fixing bar 8. At the same time, in order to reduce damage to the end of the substrate, a high temperature resistant flexible pad is provided on the inner wall of the clamping slot 9, so as to reduce the friction and collision between the substrate holder 3 and the inner wall of the clamping slot 9 when inserting and removing the clamping slot 9, thereby improving the service life of the substrate, and the flexible pad is elastic, which can play a buffering role during the insertion and removal of the substrate. Under the effect of thermal expansion and contraction, the flexible pad can strengthen the fixation of the substrate during deposition. In order to increase the use flexibility of the substrate holder 3, the first fixing bar 7 and the second fixing bar 8 are slidably arranged on the substrate holder 3 through an elastic element, and the expansion and contraction axis of the elastic element is perpendicular to the length axis of the first fixing bar 7. Firstly, the sliding first fixing bar 7 and the second fixing bar 8 can adapt to substrates of different sizes, and secondly, the rebound performance of the elastic element can provide a clamping force to fix the substrate, which helps to prevent the deformation or displacement of the substrate.

[0031] A rotating structure is provided at the bottom of the substrate holder 3, and the rotating structure includes a rotating motor, a rotating base 4 and a support rod 5. The housing 1 of the rotating motor is fixed to the outer bottom of the housing 1, and the output end of the rotating motor passes through the bottom of the housing 1 and is fixedly connected to the bottom of the rotating base 4. One end of the support rod 5 is fixedly connected to the rotating base 4, and the other end is connected to the bottom of the substrate holder 3.

[0032] In this embodiment, the support rod 5 is a hollow structure, and the liquid inlet pipeline 10 and the liquid outlet pipeline 11 are both located in the support rod 5. A partition is provided inside the support rod 5, and the liquid inlet pipeline 10 and the liquid outlet pipeline 11 are respectively located on both sides of the partition. The partition divides the internal space of the support rod 5 into two independent parts, which are used to accommodate the liquid inlet pipeline 10 and the liquid outlet pipeline 11 respectively. This separation ensures that the coolant does not interfere with each other during the inflow and outflow process, maintains a clear path and flow direction of the fluid, and reduces the heat exchange between the liquid inlet and liquid outlet pipelines 11, thereby reducing heat loss.

[0033] A crystal oscillator is provided on the substrate holder 3, and the deposition rate is monitored in real time through the crystal oscillator, thereby realizing monitoring of the film thickness, which helps to optimize the deposition process and improve the deposition quality and uniformity.

[0034] The inside of the housing 1 is also connected to a vacuum pump, which is used to provide vacuum conditions during deposition, thereby ensuring the deposition quality.

[0035] A cold deposition preparation method for a formamidinium halide material, using a cold deposition coating device for a formamidinium halide material, the preparation method utilizes the fact that a formamidinium halide material in a dispersed state is most likely to be deposited first in a region with a lower temperature, and a variable temperature and rotatable substrate device is designed to achieve preferential deposition and precise control of the formamidinium halide material, and specifically comprises the following steps: S1, fix the deposition surface of the substrate in a back-to-back manner in a substrate fixture of the substrate holder 3; S2, turning on the heating switches of the evaporation source 2 and the heating belt at the same time, so that the formamidinium halide material is vaporized, and the temperature of the shell 1 and the cavity is increased, and the temperature inside the cavity is controlled within 100-250°C; S3, rotating the substrate holder 3, opening the cooling structure to cool the substrate, when the temperature of the substrate is lower than the internal temperature of the cavity, the formamidinium halide material begins to deposit on the surface of the substrate, completing the preparation of the formamidinium halide film.

[0036] When in use, the temperature of the housing 1 is higher than that of the substrate holder 3. This is because the formamidinium halide material in a dispersed state is most likely to be deposited first in a region with a lower temperature. The design of a temperature-variable and rotatable substrate holder 3 can achieve preferential deposition and precise control of the formamidinium halide material. That is, when the temperature of the housing 1 is higher than that of the substrate holder 3, the formamidinium halide material will preferentially deposit on the substrate holder 3 with a lower temperature after evaporation. The preferential deposition of the formamidinium halide material is achieved through the temperature difference. By adjusting the temperature difference between the housing 1 and the substrate holder 3, the deposition rate and thickness of the formamidinium halide material can be precisely controlled. The rotating substrate holder 3 can eliminate the thickness difference caused by uneven deposition rate and improve the uniformity of the film.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and substitutions, and these modifications and substitutions are also within the scope of protection covered by the claims.

Claims

1. A cold deposition coating device for formamidinium-based halide materials, characterized in that: The invention comprises a shell (1), an evaporation source (2) and a substrate holder (3), wherein the evaporation source (2) and the substrate are both located inside the shell (1), a formamidinium halide material is placed in the evaporation source (2), a heating belt is embedded inside the shell (1), the evaporation source (2) is arranged at the center of the shell (1), and the heating belt and the evaporation source (2) are temperature-controlled by separate electric heating methods; the substrate holder (3) is arranged around the evaporation source (2) according to the design position of the cavity; a cooling structure is arranged inside the substrate holder (3), substrate clamps are arranged on both sides of the substrate holder (3), the substrate is fixed on the substrate clamps, and a rotating structure is arranged at the bottom of the substrate holder (3); a vacuum pump is also connected inside the shell (1); when in use, the temperature of the shell (1) is higher than the temperature of the substrate holder (3).

2. The cold deposition coating device of formamidinium-based halide material according to claim 1, characterized in that: The rotating structure comprises a rotating motor, a rotating base (4) and a supporting rod (5); a housing (1) of the rotating motor is fixed to the outer bottom of the housing (1); an output end of the rotating motor passes through the bottom of the housing (1) and is fixedly connected to the bottom of the rotating base (4); one end of the supporting rod (5) is fixedly connected to the rotating base (4), and the other end is connected to the bottom of a substrate holder (3).

3. The cold deposition coating device of formamidinium-based halide material according to claim 2, characterized in that: The support rod (5) is a hollow structure. The cooling structure comprises a liquid inlet pipeline (10), a regulating pipeline (6) and a liquid outlet pipeline (11). The liquid inlet pipeline (10) and the liquid outlet pipeline (11) are both located in the support rod (5). One end of the liquid inlet pipeline (10) is connected to an external liquid tank, and the other end is connected to a liquid inlet end of the regulating pipeline (6). The regulating pipeline (6) is embedded in the substrate holder (3). The liquid outlet end of the regulating pipeline (6) is connected to a liquid inlet end of the liquid outlet pipeline (11), and the liquid outlet end of the liquid outlet pipeline (11) is connected to the external liquid tank. The external liquid tank contains cooling liquid. A temperature control electrode is arranged at the bottom of the external liquid tank. The temperature control electrode is connected to an external power supply.

4. The cold deposition coating device of formamidinium-based halide material according to claim 3, characterized in that: The regulating pipeline (6) is arranged in a serpentine shape inside the substrate holder (3).

5. The cold deposition coating device of formamidinium-based halide material according to claim 3, characterized in that: A partition is provided inside the support rod (5), and a liquid inlet pipeline (10) and a liquid outlet pipeline (11) are respectively located on both sides of the partition.

6. The cold deposition coating device of formamidinium-based halide material according to claim 3, characterized in that: A flow regulating valve is provided on the liquid inlet pipeline (10).

7. The cold deposition coating device of formamidinium-based halide material according to claim 3, characterized in that: A crystal oscillator is arranged on the substrate holder (3).

8. The cold deposition coating device of formamidinium-based halide material according to claim 1, characterized in that: The substrate clamp comprises a first fixing bar (7) and a second fixing bar (8), the first fixing bar (7) and the second fixing bar (8) are connected to the vertical surface of the substrate holder (3) in parallel and at intervals, and the substrate is clamped between the first fixing bar (7) and the second fixing bar (8).

9. The cold deposition coating device of formamidinium-based halide material according to claim 7, characterized in that: The first fixing strip (7) and the second fixing strip (8) are slidably arranged on the substrate holder (3) via an elastic element, and the telescopic axis of the elastic element is perpendicular to the length axis of the first fixing strip (7).

10. A method for preparing a formamidinium-based halide material by cold deposition, using the formamidinium-based halide material cold deposition coating device as claimed in any one of claims 1 to 9, characterized in that: The preparation method utilizes that the formamidinium halide material in a dispersed state is most likely to be deposited first in a region with a lower temperature. A variable temperature and rotatable substrate device is designed to achieve preferential deposition and precise control of the formamidinium halide material. The method specifically includes the following steps: S1, fixing the deposition surface of the substrate in a back-to-back manner in a substrate fixture of a substrate holder (3); S2, turning on the heating switches of the evaporation source (2) and the heating belt at the same time, so that the formamidinium halide material is vaporized, and at the same time the temperature of the shell (1) and the cavity is increased, and the temperature inside the cavity is controlled within 100-250° C.; S3, rotating the substrate holder (3), opening the cooling structure to cool the substrate, when the temperature of the substrate is lower than the internal temperature of the cavity, the formamidinium halide material begins to deposit on the surface of the substrate, completing the preparation of the formamidinium halide film.

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